Dispersion and process of producing same



Patented Feb. 24, 1931 UNITED STATES PATENT OFFICE JACOB MITCHELL IAIN, OFBBOOKLYN, NEW YORK, ASSIGNOR TO THE FLINTKOTE COM- rm, OF BOSTON, MASSAGHUSEITS, A CORPORATION OI MASSACHUSETTS DISIfEISION AND PROCESS OF iIROD'U'GIIEI'G- SAME lN'o Drawing. 7 Thisinvention relates to the art of making aqueous dispersions of bituminous and like substances normally immiscible with water. Bituminous dispersions as known to '5 the art at the present time, may be produced by various processes and with the aid of numerous substances functioning as dispersing media to assist in causing subdivision of the bitumen into dispersed particles of more or 10 less fine size. Generally speaking, dispersion may be effected by at least two distinct types of operations. In one type, the dispersing medium functions to reduce the surface tension of the aqueous medium, this being generall evidenced by its ability to foam so that ispersion takes place largely by virtue of this property, this type of operation being normally operable within considerable temperature latitudes within which the phases are liquid. Under these conditions, relatively sli ht mechanical action is necessary to pro uce the dispersion and generally, no great difliculty is ex erienced in attaining fine particle size. boap and soapy materials are among the substances which function in the foregoing manner to produce dispersion, although, of course, other materials capable of reducing surface tension of the aqueous medium may be utilized. q

The dispersion products produced under the foregoing conditions and with the aid of the afor'enamed emulsifying media are frequently unstable, and particularly when the amount of emulsifying media employed approximates the minimum that will effect a material reduction in the surface tension, the product is unable to maintain the dispersed state upon standing for substantial periods of time and hence breaks down upon standing. With quantities of the dispersing media in excess of the critical minimum referred to, the product may be made to maintain its dispersed state for substantial periods of time although, of course, even in such case the introduction ofelectrolytes and similar influences, are generally sufiicient to cause a breaking of the dispersion. In the other typeofoperation, the emulsifiers employed operate under conditions in- Application filed November 21, 1928. Serial No. 321,045.

fluenced largely by the temperature and the viscosity of the aqueous dispersion medium. Th1s type of operation requires carefully controlled temperatures and considerable internal friction in the mass undergoing disperslon with consequent power consumption in order to produce dispersions of desirable character. In general, paste forming powders such as finely divided clays, bentonite and the like, are examples of dispersing media employed in conjunction with this second type of operation. When these materials are thus employed to produce fine subdivision ofthe dispersed particles, the resultant product will be comparatively stable, not only in its ability to maintain the dispersed state upon standing for considerable periods of time, but also to the action of most electrolytes.

The object of the present invention is to utilize the advantages incident to the type of operation first above described for the production of dispersions which in certain respects, possess the stability characteristic of the products formed under the second .type of operating conditions as above described. V

Another object of the invention resides in the provision of a methodfor utilizing materials capable of reducing the surface ten- S1011 of the aqueous medium in the production of dispersions, the amount of surface tension reducing material employed being regulated to the minimum necessary to provide, in conjunction with materials falling under the second group, a sufficient reduction in surface tension to enable the combined media to disperse bitumen in a manner characteristic of the first type of operation above described, yet having far greater stability 90 (so far as maintaining the dispersed state is concerned) than is normally possible with such type of operation, the resultant product more nearly resembling in this respect the product produced with far greater quantity of emulsifying agent of the first type or the product made in accordance with the second type of operation.

Other objects ofthe invention will hereinwe after more fully appear from the following description of the inventiom In carrying out my invention, I may combine with bentonite and/or clay or other colloidal powders capable of forming a paste or viscous suspension with water, an agent capable of lowering the surface tension of the aqueous medium so as to render the bitumen more readily susceptible to rapid subdivision into fine particles by a comparatively light stirring or agitating action. By thus utilizing an agent for reducing the surface tension of the asphalt, I am enabled to produce dispersions without requiring a very nice and skilled control of the temperature conditions during the operation, and at the same time producing a relatively stable product due to the presence therein of the clay, bentonite or other mineral powder, and without which the product would be comparatively unstable.

In one embodiment of my invention, I have dispersed a relatively soft asphalt of Columbian stock, the asphalt having a melting point of say between 7 0 and 90 degrees F., by combining about eight parts of bentonite with one part of soap (sodium oleat-e) in a solution of about 400 parts of water and dispersing therein approximately 1200 parts by weight of the asphalt, the asphalt in hot molten state being added to the bentonitesoap suspension accompanied by a stirring action performed in any suitable equipment designed for the purpose. The final dispersion as thus produced, as will be seen from the figures given, contains approximately 75% of the asphalt, 25% of water, 0.5% bentonite and of soap. WVith such a small proportion of the soap, this product, in the absence of the bentonite, would normally be comparatively unstable and in fact, breaks down upon standing for any considerable length of time, say a few weeks. Due to the presence of the bentonite, however, this disruption of the product is prevented. On the other hand, it will be apparent to those skilled in the art, that in order to satisfactorily disperse asphalt of such a soft nature with a small amount of material like bentonite, a very careful control of the tempera ture conditions during the operation would be necessary, but that, in accordance with my invention, the necessity for this control is eliminated due to the function of the soap, the operation thus resembling the dispersion of asphalt with materials like soap, in that the same may be carried on at relatively high temperatures varying over a considerable range, which would ordinarily seriously encumber the operation when using material such as bentonite or the like.

In another embodiment of my invention I may use saponin as the surface tension reducing material in lieu of soap. To produce dispersion with this material I may combine the same with a paste forming colloid such as bentonite in proportions say of one part of the saponin to say one to about three parts of bentonite. With these proportions I may produce a stable dispersion of asphalt of the above described character and containing about 7 O to 75% of the asphalt, 20 to 25% of water, about saponin, and 4% to benonite.

I may also carry out my invention by combining soap with an aqueous mixture of gelatin in quantities to reduce sufliciently the surface tension of the aqueous medium so as to enable satisfactory dispersion to take place. With this procedure and using approximately two parts of gelatin to each part of soap, the final dispersion may contain approximately to of the bitumen, about soap, gelatin, and the balance water.

The last named procedure may also be carried out with the substitution of saponin' in lieu of the soap, in which event the dispersion produced may contain about saponin, gelatin, the bitumen and water content being approximately the same as that stated.

It should be understood that in the illustrations hereinabove given, the stability of the product may be even further increased within certain limits, by increasing the relative amount of the bentonite or similar substance present in the dispersion, this regulation of the stability of the final product, obviously depending upon the degree of stability desired for the particular use to which it is to be applied.

The present invention produces a product ordinarily requiring a rather accurate control by a process eliminating the requirement for such control. p

I claim as my invention:

1. A process of producing relatively stable aqueous dispersions of water-immiscible material containing in excess of fifty parts of which comprises making an aqueous suspension of paste-forming colloidal material and modifying said suspension by adding thereto an agent of such a character and in such an amount as to substantially reduce the surface tension of the aqueous medium whereby to enable dispersion to take place by relatively light agitation, and then mixing waterimmiscible material with said modified suspension and dispersing same by a relatively light agitation only and substantially independently of the viscosity of the aqueous mixture.

2. A process of producing relatively stable aqueous dispersions of water-immiscible material containing inexcess of fifty parts of said water-immiscible material to one part of dispersing agent on the basis of weight, which comprises making an aqueous suspension of paste-forming colloidal material and modifying said suspension by adding thereto an agent of such character and in such an amount as to substantially reduce the surface tension of the aqueous medium whereby to enable dispersion to take place by relatively light agitation and substantially independently of the viscosity of the aqueous mixture, and dispersing same by agitating action of the type characteristic of the agitating action requlred to disperse the same material with soap or soap-like dispersing agent.

3. A process of producing relatively stable aqueous dispersions of water-immiscible material containing in excess of fifty parts of said water-immiscible material to one part of dispersing agent on the basis of weight, which comprises making an aqueous suspension of paste-forming colloidal material and modifyingssaid suspension by adding thereto a water soluble modifying agent of such character and in such an amount as to reduce the surface tension of the aqueous medium sufliciently to enable dispersion to take place by relatively light agitation only and substantially independently of the viscosity of the aqueous medium and then mixing waterimmiscible material with said modified suspension and dispersing same by relatively light agitation only.

4. A process of producing relativel stable aqueous dispersions of water-immisci 1e material containing in excess of fifty parts of said water-immiscible material to one part of dispersing agent on the basis of weight, which comprises making an aqueous suspension of paste-forming colloidal materialand modifying said suspension by adding there to an agent capable of emulsifying said water-immiscible material by the reduction of surface tension in an amount less than would be sufiicient to produce an emulsion of sufficient stability to withstand disruption upon long standing, and then mixin water-immiscible material with said modi ed suspension and dispersing same by relatively light agitation only.

5. A process of producing relatively stable aqueous dispersions of waterdmmiscible material containing in excess of fifty parts of said water-immiscible material to one part of dispersing agent on the basis of weight, which comprises making an aqueous suspension of bentonite and modifying said suspension by adding thereto soap in an amount suficient to reduce the surface tension of the aqueous medium to enable disper ion to take place by relatively light agitation only, and then mixing water-immiscible material with said modified suspension and dispersing same by relatively light agitation only,

In testimon whereof I afix my signature.

J 00B MITCHELL FAIN, 

